Field of the Invention
The present disclosure relates to a pneumatic tire in which a main groove extending in a tire peripheral direction is formed in a tread portion, and a tie bar protruding at a predetermined height is formed in a groove bottom of the main groove.
Description of the Related Art
As shown in FIG. 11A, in a pneumatic tire having a main groove 1 which extends in a tire peripheral direction PD, and land portions 2 which are comparted by the main groove 1, in a tread portion, it can be thought that a pair of notches 3 which are open to a tread surface and are concave portions are formed at mutually facing positions, in side surfaces of two land portions 2 which are adjacent across the main groove 1, for improving a traction.
In the structure in which the notches are formed in the land portions, a difference is generated between an energy which acts on an edge e1 in a step-in side of the notch 3 and an energy which acts on an edge e2 in a kick-out side, as shown in a plan view in FIG. 11B. As a result, a so-called uneven wear that an amount of wear of the both is biased tends to be generated. In order to reduce the difference of the energies acting on both the edges so as to suppress the uneven wear, there can be thought a structure in which a tie bar 4 protruding at a predetermined height from a groove bottom of the main groove 1 is provided, and the tie bar 4 connects between the paired notches 3, as shown in FIGS. 11A and 11B.
Although the purpose is absolutely different, patent document 1 discloses a tire in which a wear indicator (a projection) for indicating a replacement timing due to a tire wear is formed in a groove bottom of a main groove, wherein a concave portion is provided in a side surface of the main groove for solving lack of rubber due to the wear indicator, and the rubber corresponding to the concave portion is charged in the wear indicator. It is thought that a depression in the side surface of the main groove does not have a length which is necessary for obtaining traction.